I'm taking care of a friend's daughter-she is 14-and she poops herself.?

I'm taking care of a friend's daughter for about a month-she is 14-and she poops herself almost every day. She is flippant about it, and says that she 'likes it' and that I should keep out of it. She doesn't wear diapers. What should I do about her attitude, and the fact that she acts like a baby?